As concern over global warming grows, urban planning advocates have jumped on the bandwagon by claiming cities should reduce their carbon footprints by investing more in transit and compact development. However, these claims are not supported by the data, most of which show that transit and dense development are no more environmentally friendly than autos and low-density suburbs.
This debate is an echo of efforts to reduce toxic air pollution, such as carbon monoxide and smog, which began in 1970. Some said we should encourage people to drive less and take transit more. Others said we should use new technologies to make the cars we drive cleaner.
Looking back, we now know that technical solutions were phenomenally successful: though we drive three times as much as we did in 1970, total auto emissions are down by about two thirds. Meanwhile, attempts to change people's lifestyles were miserable failures. Despite investing hundreds of billions in transit, the share of people and commuters riding transit has declined throughout the U.S.
A new study from the Brookings Institution ignores this history when it recommends that cities invest in transit and compact development to reduce their carbon footprints. On a per-passenger-mile basis, transit buses emit more greenhouse gases than an average SUV, and most light-rail lines emit more greenhouse gases than the average automobile. Denver's light rail is even worse than the average bus.
Meanwhile, data gathered by the Australian Conservation Foundation revealed that per-capita carbon emissions from people living in single-family homes are lower than people living in low-rise, mid-rise, and high-rise apartments and condos. This suggests that compact development will increase, not reduce, our carbon footprint.
Even to the extent that transit and compact development could reduce greenhouse gas emissions, we have to ask: at what cost? A recent report published by McKinsey, the famous consulting firm, found that America could significantly reduce its total greenhouse emissions by investing in technologies that cost no more than $50 per ton of reduced emissions. Neither compact development nor transit would meet this cost test.
More efficient cars
Instead, McKinsey urged auto manufacturers to make cars out of lighter weight, energy-saving materials. This would pay for itself in lower fuel costs.
Traffic congestion causes motorists to waste nearly 3 billion gallons of fuel and spew 26 billion tons of CO2 into the air each year. Relieving that congestion by tolling freeways can reduce greenhouse emissions at practically no cost, while coordinating traffic signals on city streets will reduce emissions at a cost of about $11 per ton.
Transit improvements, however, will cost far more than $50 a ton. Converting buses to biodiesel, for example, costs nearly $200 per ton. Using buses with hybrid motors costs more than $1,000 a ton.
When you count the carbon footprint from building rail transit, rails almost always lose, especially in regions where fossil fuels are used to generate most electricity. The Minneapolis light rail is one of the more successful lines in the country (which isn't saying much). It operations produce less carbon emissions than the average auto, but at a cost of nearly $5,000 per ton—not counting the carbon emitted during construction.
Even in regions that rely on hydro and other renewable energy for electricity, rail transit loses when you count the carbon emissions from the feeder bus systems needed to support the rail lines. Transit systems in Portland, Sacramento, and other cities ended up consuming more energy and emitting more greenhouse gases, per passenger mile, after they open new rail lines because of extensive, but little-used, feeder bus networks.
Nor is there any evidence that compact development can cost-effectively reduce CO2 emissions. One study found that compact development reduces emissions, but estimated the cost would be more than $60,000 per ton.
Again, better technology makes more sense than trying to change people's lifestyles. Homeowners can save more energy and greenhouse gas emissions by installing better installation than by moving into high-density developments. The concrete and steel needed to build mid-rise and high-rise apartments, for example, emit huge amounts of greenhouse gases.
If global warming is truly a problem, we can't waste resources trying to get people to make expensive and ineffective changes in their lifestyles. Anyone who recommends changing your lifestyle to reduce greenhouse gas emissions without showing you that those changes are cost effective is wasting your time and money.